design for ultimaker rev2
TRANSCRIPT
DESIGN FOR ADDITIVE MANUFACTURING
PARTICULARITIES TO BE CONSIDERED WHEN PREPARING PARTS FOR BEING PRINTED ON AN ULTIMAKER FDM PRINTER
Greta D’AngeloMartí BertranThomas J. Howard
2
AGENDA
1. Introduction on FDM and AM
2. Geometrical constraints
3. Support structures
• Avoiding support structures• Working with support structures
4. Hollowed parts and infill
5. Printing text
6. Designing mechanisms
3
FUSED DEPOSITION MODELLING
• Additive Manufacturing (AM) technologies build parts by overlapping layers of material
• Extrusion of melted material through a nozzle on a build plate
• Cartesian coordinates
• Tolerance (in vertical direction) is determined by the diameter of the nozzle
• Examples: Stratasys, RepRap, Ultimaker
4
1 2 3
456
WORKFLOW
Design a part • CAD program
Export to STL• All packages can do
it
Check STL• Netfabb
Slice and generate Gcode• Cura
Upload Gcode to printer• SD card
Start printing!• Ultimaker’s
controller
5
MATERIAL PROPERTIES
• Ultimaker uses 3mm PLA filament
• Biodegradable thermoplastic
• Highly anisotropic mechanical properties
• Several colors available
PLA Polymer
Physical property Specific Gravity [g/cm3] 1,25
Melt Index [g/10min] (190º/2,16kg)
4 - 8
6
GEOMETRICAL CONSTRAINTS
Minimum Wall thickness:
• Vertical and tilted walls:
• 2mm and above. Recommended• Horizontal walls:
• 1mm and above is correct
Definition 0,5mm minimum details noticed
Accuracy 0,3% (min +/-0,3mm)
Avoid warping Large horizontal and thick surfaces are likely to warp, skip using them if you can.
Overall maximum dimensions 150*150*150 mm (x*y*z)
7
FACING GEOMETRICAL CONSTRAINTS
• Scale parts
• After scaling check that your part meets the geometrical constraints
• Notice that wall thicknesses will be scaled down as well, and may not meet the requirements
8
SUPPORT STRUCTURES
• Support structures are features added below part areas where there’s nothing
• They prevent layers to collapse during it’s build up and allow part manufacturability
9
AVOIDING SUPPORT STRUCTURES: PART ORIENTATION
• Part orientation is a key factor to achieve a good print
• In many cases we can avoid or at least reduce the amount of supports required
• Resolution is better in the z-axis faces (vertical) than XY (horizontal) stepping
• Mechanical properties are better in the XY plane
10
PART ORIENTATION
Staircase effect
Smooth surfaces
11
AVOIDING SUPPORT STRUCTURES: SPLITTING PARTS
• Splitting parts is a good way to avoid using supports
• Can be done after exporting the CAD to STL by using Netfabb
• To use in extreme causes because:
• We’ll have to glue all the parts after the print
• Tolerances will not be the same
• We’ll see partition lines in our part
12
AVOIDING SUPPORT STRUCTURES: MODIFY OVERHANGING SURFACE
• The printer is able to print overhanging surfaces without support structures from a minimum angle α (>30º)
• We must do the modifications before exporting the STL file
• Small projections from the walls (<1mm) can be printed without problems
13
AVOIDING SUPPORT STRUCTURES: MODIFY OVERHANGING SURFACE
• Cura Software shows which surfaces needs support structures (<30º)
Support structures required here
14
AVOIDING SUPPORT STRUCTURES: BRIDGES
• The printer is able to print flat surfaces without supports between two walls
• Max distance between walls: 20mm
Bridge
15
AVOIDING SUPPORT STRUCTURES: BRIDGES
Bridge
Small holes doesn’t require changes
Modified hole
16
WORKING WITH SUPPORT STRUCTURES
• Accessibility: We must be able to remove SS easily
• Scaring: Avoid using them in part characteristic surfaces SS can damage the finishing of these surfaces and also the tolerances
• Avoid using SS below thin walls or slender and fragile parts, they can break easily while removing them
17
HOLLOWED PARTS AND INFILL
• Hollow can be achieved when gcode is generated, by changing parameters of Cura
• We can also choose how much infill (%) we want inside the part, by default we use between 30% and 40%
• Design Tip: design always solid parts
Infill
Perimeters
Gcode Cura View
18
HOLLOWED PARTS AND INFILL
By reducing the infill:
• Build time decreases
• Used material decreases
• It helps to avoid warping
• Strength doesn’t decreases that much
19
PRINTING TEXT
• Text in vertical faces will be more visible and accurate
• If it’s not possible, the text at the bottom of the part (the face that sticks to the building platform), must be engraved.
• In the top face of the part, text can be either engraved/embossed
• It should be at least 0,8mm high and 0,8mm wide to be visible.
20
PRINTING TEXT
Horizontal engraved text
Vertical embossed text
Vertical engraved text
21
DESIGNING MECHANISMS
Joints clearance:
• Design adjustments with a gap of more than 0,3mm between mobile parts
22
DESIGNING MECHANISMS
Part orientation
• Try to print the areas of parts that has to fit each other in the same orientation (different orientations could have different deviations/tolerances)
Integrated nut holders embossed is better than engraved!
23
QUESTIONS?